Members of the flagellate protozoan family Trypanosomatidae are parasites; including pathogens, such as Trypanosoma cruzi (Chagas' disease) and members of the genus Leishmania (visceral, cutaneous and mucocutaneous infections), which are responsible for considerable human disease. These organisms contain significant quantities of complex carbohydrates; although they lack glycogen-like polysaccharides for energy reserve. Uncharacterized carbohydrates isolated from these protozoa have been used for serodiagnosis of these diseases. Part of the purpose of this research plan is to characterize these constituents. Complex carbohydrates will be prepared by solvent extraction, cell fractionation and chromatographic methods from several members of this family including Crithidia spp. (parasites of insects), T. cruzi and Leishmania spp. cultured on cell-free media. The isolated components will be characterized by compositional analysis and as to intracellular localization. Antisera, from rabbits immunized with the components, will be used to detect these constituents and they will be used to determine cross reactivity. Analyses will also be made of complex carbohydrates from other stages of these parasites which are maintained in tissue culture or suitable mammalian hosts. The relationship of these purified complex carbohydrates to circulating antigens in mammals infected with these organisms and to exantigens (excretion factors) secreted into media will also be examined. Further, the role of these constituents in the growth of and infection produced by these parasites will be considered. This research plan also proposes to study the cell membranes and cell surface of these protozoa. Initially, efforts will be made to determine the contribution of complex carbohydrates and glycoconjugates to the membrane. Subsequently various cell surface labeling methods will be used to determine the deposition of these and other components. In addition, absorbed host components on the surface will be characterized. These studies may be useful in analyzing the mechanisms of parasitism in these hemoflagellates.